Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 19 Nov 2001 13:18:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 19 Nov 2001 13:18:17 -0500 Received: from h24-78-175-24.nv.shawcable.net ([24.78.175.24]:46211 "EHLO oof.localnet") by vger.kernel.org with ESMTP id ; Mon, 19 Nov 2001 13:18:04 -0500 Date: Mon, 19 Nov 2001 10:18:03 -0800 From: Simon Kirby To: linux-kernel@vger.kernel.org Subject: Re: [VM] 2.4.14/15-pre4 too "swap-happy"? Message-ID: <20011119101803.A25117@netnation.com> In-Reply-To: <200111141243.fAEChS915731@neosilicon.transmeta.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.23i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 14, 2001 at 08:34:12AM -0800, Linus Torvalds wrote: > That's normal and usually good. It's supposed to swap stuff out if it > really isn't needed, and that improves performance. Cache _is_ more > important than swap if the cache is active. We have to remember that swap can be much slower to read back in than rereading data from files, though. I guess this is because files tend to be more often read sequentially. A freshly-booted box loads up things it hasn't seen before much faster than a heavily-swapped-out box swaps the things it needs back in...window managers and X desktop backgrounds, for example, are awfully slow. I would prefer if it never swapped them out. This is an annoying situation, though, because I would like some of my unused daemons to be swapped out. mlocking random stuff would be worse, though. > HOWEVER, there's probably something in your system that triggers this too > easily. Heavy NFS usage will do that, for example - as mentioned in > another thread on linux-kernel, the VM doesn't really understand > writebacks and asynchronous reads from filesystems that don't use buffers, > and so sometimes the heuristics get confused simply because NFS activity > can _look_ like page mapping to the VM. I've been copying about 40 GB of stuff back and forth over NFS over switched 100Mbit Ethernet lately, so I can say I'm definitely seeing this. :) It also seems to happen when I "pull" over NFS rather than "push" (eg: I ssh to a remote machine and "cp" with the source being an NFS mount of the local machine)...the 2.4.15pre1 local machine tends to swap out while this happens as well. Simon- [ Stormix Technologies Inc. ][ NetNation Communications Inc. ] [ sim@stormix.com ][ sim@netnation.com ] [ Opinions expressed are not necessarily those of my employers. ] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/